Date: Thu, 7 Apr 2005 09:55:16 -0700 (PDT)
From: Linus Torvalds <torvalds@osdl.org>
To: Stas Sergeev <stsp@aknet.ru>
cc: Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org,
       Andrew Morton <akpm@osdl.org>, Petr Vandrovec <VANDROVE@vc.cvut.cz>
Subject: Re: crash in entry.S restore_all, 2.6.12-rc2, x86, PAGEALLOC
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On Thu, 7 Apr 2005, Stas Sergeev wrote:
>
> 1. Does the "later sti" fixes the problem
> also in case of an NMI? I mean, why can't
> you just be NMI'ed before you did sti?
> NMI uses the restore_all too IIRC.

The NMI code had better be really careful, and yeah, I suspect it needs 
fixing.

> 2. How can one be sure there are no more
> of the like places where the stack is left
> empty?

That's a good argument, and may be the strongest reason for _not_ doing 
the speculation. However, I don't think it really can happen anywhere 
else. 

If people feel very nervous about the speculation, we can certainly just 
make it do the two branches. It _is_ a hotspot, though, and the 
optimization of the speculatiom may well be worth it.


		Linus
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